Plunger seal for pump

ABSTRACT

There is provided a plunger seal ( 1 ) for a fuel injection pump for a direct-injection gasoline engine, in which, even if a resin material is used for a fuel seal member ( 12 ), the plunger seal can be made compact, sealing ability is increased, and assembling man-hours can be reduced, and in which set sealing performance can be achieved when a U-shaped elastic member ( 33 ) for applying an energizing force in a diametrical direction is used in a groove ( 41 ) formed in the fuel seal member ( 12 ). The resin fuel seal member ( 12 ) and an oil seal member ( 13 ) are assembled to form one seal system. Further, when the U-shaped elastic member ( 33 ) is installed in the groove ( 41 ), an axial position (L 1 ) of an end surface ( 44   a ) at the side opposite to the sealed object of a fixing collar ( 44 ) formed on an inner peripheral surface of the groove ( 41 ) is positioned at the side (B) opposite to the sealed object than the axial position (L 2 ) of a leading end portion ( 15   b ) of a seal lip ( 15 ) of the fuel seal member ( 12 ).

This is a nationalization of PCT/JP05/005084 filed Mar. 22, 2005 andpublished in Japanese.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plunger seal for a pump which is usedas a reciprocating seal of a high-pressure fuel pump in a fuel injectionpump for a direct-injection gasoline engine, and used for all other oilpressure, air pressure and water pressure equipments.

2. Description of the Conventional Art

The direct-injection gasoline engine is structured such as to directlyinject a high-pressure fuel into a cylinder so as to burn for thepurpose of a regulation of exhaust gas, an improvement of specific fuelconsumption and the like in recent years. Since a high pressureperformance is demanded in the fuel injection pump used for directlyinjecting the high-pressure fuel, a performance standing against a highpressure is demanded in a plunger seal for the pump used in the fuelinjection pump.

Conventionally, as the plunger seal for the pump used in the fuelinjection pump, there has been known a rubber lip type seal memberintegrally having a fuel seal lip sealing the fuel such as the gasolineor the like at high pressure in a sealed object side, and an oil seallip sealing an oil existing in an opposite side to the sealed object forcooling and lubricating (refer to Japanese Unexamined Patent PublicationNo. 8-68370). However, since a material of the seal lip is constitutedby the rubber, there is a problem that a sealing function can not besufficiently satisfied with respect to a lack of pressure tightness dueto the high pressure and a lack of fuel resistance accompanied by anincrease of an alcoholic content in the fuel.

Accordingly, there has been proposed a structure in which the fuel seallip is made of the resin and is independently provided from the rubberoil seal lip, whereby it is possible to maintain the pressure resistanceeven if the pressure of the high-pressure fuel becomes higher, and it ispossible to prevent a swelling and a reduction of hardness and strengthwith respect to the alcohol contained fuel or the like (refer to thepatent document WO 02/099320A1). However, since the fuel seal lip andthe oil seal lip are independently provided, an installation space isincreased, so that there is a problem that it is impossible to respondto a demand for a compact structure, and it is impossible to secure astable seal performance with respect to a higher performance requirementof the fuel pump. Further, since a demand for a low cost is increased,it is necessary to respond to this. It is necessary to reduce a numberof seals for reducing an assembling man-hour.

Further, there has been known that, when a metal spring having anapproximately U-shaped cross section and applying an energizing force ina diametrical direction is installed in a groove formed in the rubberfuel seal lip, a fixing collar for preventing the metal spring fromjumping out is provided in an opening portion of the groove (refer toJapanese Patent No. 2651407). However, if the fixing collar is providedin the case that the fuel seal lip is constituted by the resin material,a shape thereof becomes complicated, it is hard to manufacture the seallip of the resin material by a normally used injection molding machine.Accordingly, there has been proposed that an inner surface of the groveis formed flat while abolishing the fixing collar, in the case that theresin fuel seal lip in which the metal spring having the approximatelyU-shaped cross section is installed is manufactured by the injectionmolding machine (refer to Japanese Patent No. 2955822).

Further, as shown in FIG. 16, in the conventional fuel seal lip 101using the rubber material, a shape of the seal lip 101 is specified bysetting angles α and β formed by both side surfaces 103 and 104 of theseal lip 101 with respect to a plunger 102 at a time of installing theplunger 102, and a surface pressure gradient P generated in a contactsurface of the seal lip 101 at a time of installing the plunger 102 iscontrolled as shown in FIG. 17, whereby it is possible to control athickness t of a seal medium interposed between the seal lip 101 and theplunger 102 so as to secure a sealing performance (a leak amount) inaccordance with a set seal performance. However, if the material of thefuel seal lip 101 is changed to the resin such as PTFE or the like, theangle α and β corresponding to the shape of the seal lip 101 aredeformed and changed by use on the basis of a creep characteristic.Accordingly, the surface pressure gradient P generated in the contactsurface of the seal lip 101 is changed, and it is hard to secure theseal performance (the leak amount) in accordance with the set value.

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The present invention is made by taking the points mentioned above intoconsideration, and an object of the present invention is to provide aplunger seal for a pump used in a fuel injection pump for adirect-injection gasoline engine, which can achieve a compact structure,an improvement of pressure resistance and sealing performance, a costreduction and a reduction of an assembling man-hour even if a resinmaterial is used for a fuel seal member for the purpose of the pressureresistance and a heat resistance.

Another object of the present invention is to provide a plunger seal fora pump which can secure a preset sealing performance (leak amount) evenif a shape of a seal lip is deformed by use, in the case that a metalspring applying an energizing force in a diametrical direction andhaving an approximately U-shaped cross section is installed in a grooveformed in a fuel seal member using the resin material.

Means for Solving the Problem

In order to achieve the objects mentioned above, in accordance with afirst aspect of the present invention, there is provided a plunger sealfor a pump, the plunger seal being provided in an annular space betweena shaft reciprocating within a high-pressure fuel injection pump and ahousing, sealing a high-pressure fuel corresponding to a sealed objectand sealing an oil in an opposite side to the sealed object, wherein aseal system is structured by assembling a resin fuel seal member slidingso as to be freely brought into close contact with the shaft and sealingthe high-pressure fuel, and an oil seal member positioned at theopposite side to the sealed object from the fuel seal member and mainlysealing the oil.

Further, in accordance with a second aspect of the present invention,there is provided a plunger seal for a pump as recited in the firstaspect mentioned above, wherein an elastic member for applying anenergizing force in a diametrical direction to a seal lip of the fuelseal member is installed to the fuel seal member.

Further, in accordance with a third aspect of the present invention,there is provided a plunger seal for a pump as recited in the first orsecond aspect mentioned above, wherein the oil seal member is integrallyformed with the fuel seal member made of the resin.

Further, in accordance with a fourth aspect of the present invention,there is provided a plunger seal for a pump as recited in any one of thefirst to third aspects mentioned above, in which a U-shaped elasticmember is installed in a groove open to a sealed object side formed inthe fuel seal member, wherein an axial position of a leading end surfaceof the U-shaped elastic member locked to a fixing collar provided on atleast one inner surface side of the groove is positioned at the oppositeside to the sealed object from an axial position of a leading endportion of the seal lip formed in the fuel seal member.

Further, in accordance with a fifth aspect of the present invention,there is provided a plunger seal for a pump as recited in the fourthaspect mentioned above, wherein a distance between the axial position ofthe leading end portion of the seal lip and the axial position of theleading end surface of the U-shaped elastic member locking to the fixingcollar is 20% or less of a distance between the axial position of theleading end portion of the seal lip and an axial position of a rootportion of the seal lip.

Effect of the Invention

The present invention achieves the following effects.

In the plunger seal for the pump in accordance with the first aspect ofthe present invention provided with the structure mentioned above, sincethe material of the fuel seal member is constituted by the resinmaterial, it is possible to sufficiently maintain a pressure resistanceeven in response to the high pressure requirement of the fuel or thelike, the swelling and the reduction of the hardness and the strengthare not generated with respect to the lack of fuel oiliness caused by anincrease of an alcoholic content in the fuel, and it is possible toimprove an abrasion resistance. Further, since the fuel seal member andthe oil seal member are assembled without being provided independentlyso as to structure one seal system, a compact structure is obtained soas to achieve a cost reduction, and it is possible to reduce anassembling man-hour.

Further, in the plunger seal for the pump in accordance with the secondaspect, since the elastic member for applying the energizing force inthe diametrical direction to the fuel seal member is installed, it ispossible to compensate a creep characteristic caused by setting thematerial of the fuel seal member to the resin, and it is possible tosecure a more improved sealing performance.

Further, in the plunger seal for the pump in accordance with the thirdaspect, since the oil seal member is integrally formed with the resinfuel seal member, it is possible to achieve a more compact structure anda lower cost.

Further, in the plunger seal for the pump in accordance with the fourthaspect, since the axial position, at which the leading end surface ofthe U-shaped elastic member is locked to the fixing collar provided inthe opening portion of the groove, is positioned in the opposite side tothe sealed object from the axial position of the leading end portion ofthe seal lip formed in the fuel seal member, it is possible to make gooduse of an expanding force of the U-shaped elastic member for controllingthe surface pressure gradient generated in the seal lip contact surface,by controlling the distance between the axial position of the leadingend portion of the seal lip and the axial position of the leading endsurface of the U-shaped elastic member. Accordingly, even in the casethat the seal lip shape defined by the angle formed by the contactbetween the both side surfaces of the seal lip and the shaft is deformedand changed due to the use, on the basis of the use of the elasticmaterial for the fuel seal member, it is possible to control a changelevel of the surface pressure gradient generated in the seal lip contactsurface, and it is possible to secure the preset sealing performance bycontrolling a thickness of the seal medium interposed between the seallip and the shaft.

Further, in the plunger seal for the pump in accordance with the fifthaspect, since the distance between the axial position of the leading endportion of the seal lip and the axial position at which the leading endsurface of the U-shaped elastic member is locked to the fixing collar isset to be 20% or less of the distance between the axial position of theleading end portion of the seal lip and the axial position of the rootportion of the seal lip, it is possible to more easily control thesurface pressure gradient generated in the seal lip contact surface, andit is possible to secure the preset seal amount.

BRIEF EXPLANATION OF DRAWINGS

FIG. 1 is a sectional view of a plunger seal for a pump in accordancewith a first embodiment of the present invention;

FIG. 2 is a sectional view of a plunger seal for a pump in accordancewith a second embodiment of the present invention;

FIG. 3 is a sectional view of a plunger seal for a pump in accordancewith a third embodiment of the present invention;

FIG. 4 is an explanatory view of a surface pressure gradient in FIG. 3;

FIG. 5 is a sectional view of a plunger seal for a pump in accordancewith a fourth embodiment of the present invention;

FIG. 6 is a sectional view of a plunger seal for a pump in accordancewith a fifth embodiment of the present invention;

FIG. 7 is a sectional view of a plunger seal for a pump in accordancewith a sixth embodiment of the present invention;

FIG. 8 is a sectional view of a plunger seal for a pump in accordancewith a seventh embodiment of the present invention;

FIG. 9 is a sectional view of a plunger seal for a pump in accordancewith an eighth embodiment of the present invention;

FIG. 10 is a sectional view of a plunger seal for a pump in accordancewith a ninth embodiment of the present invention;

FIG. 11 is a sectional view of a plunger seal for a pump in accordancewith a tenth embodiment of the present invention;

FIG. 12 is a sectional view of a plunger seal for a pump in accordancewith an eleventh embodiment of the present invention;

FIG. 13 is a sectional view of a plunger seal for a pump in accordancewith a twelfth embodiment of the present invention;

FIG. 14 is a sectional view of a plunger seal for a pump in accordancewith a thirteenth embodiment of the present invention;

FIG. 15 is a sectional view of a plunger seal for a pump in accordancewith a fourteenth embodiment of the present invention;

FIG. 16 is a sectional view of an elastic seal lip in accordance with aprior art; and

FIG. 17 is an explanatory view of a surface pressure gradient in FIG.16.

DESCRIPTION OF REFERENCE NUMERALS

1 plunger seal for pump

2 plunger (shaft)

3 housing

11 seal member

12 fuel seal member

13 oil seal member

14 seal lip portion

15, 16 seal lip

15 a, 16 a sub lip

15 b, 16 b leading end portion

15 c, 16 c side surface

17, 18, 19 seal fixing portion

21, 22, 23 metal ring

21 a, 22 a, 23 a cylinder portion

21 b, 22 b, 23 b flange portion

31, 32 coil spring

33 metal spring (elastic member)

41 groove

42, 43 fixing and sealing portion

44 fixing collar

A sealed object side

B opposite side to sealed object

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A description will be given below of preferable embodiments inaccordance with the invention with reference to the accompanyingdrawings. In this case, a scope of the invention is not limited to thecontents described in the embodiments unless any restrictive descriptionis given.

First Embodiment

FIG. 1 is a sectional view showing a state in which a plunger seal 1 fora pump in accordance with a first embodiment of the present invention isinstalled to an annular space formed by a plunger 2 corresponding to ashaft reciprocating within a high-pressure fuel injection pump and ahousing 3.

The plunger seal 1 for the pump is used in a fuel injection pump for adirect-injection gasoline engine, and has a function of sealing a fuelsuch as gasoline or the like at high pressure existing in a sealedobject side, and a function of sealing an oil existing in an oppositeside to the sealed object for cooling and lubricating.

In FIG. 1, the plunger seal 1 for the pump is constituted by a sealmember 11, three metal rings 21, 22 and 23 holding the seal member 11,and two coil springs 31 and 32 for applying an energizing force in anaxial direction to two seal lips 15 and 16 formed in a seal lip portion14 of the seal member 11.

Three metal rings 21, 22 and 23 are constituted by the first metal ring21 fitted to an inner peripheral side of the housing 3, the second metalring 22 having a cylinder portion 22 a fitted to an inner peripheralside of the first metal ring 21 and a flange portion 22 b extendingtoward the plunger 2 from an end portion of an opposite side B to thesealed object in the cylinder portion 22 a and formed in anapproximately inverse-L shape, and the third metal ring 23 positioned inthe opposite side B to the sealed object than the flange portion 22 b ofthe second metal ring 22 and fitted to the housing 3.

The seal member 11 is structured by integrally forming the fuel sealmember 12 and the oil seal member 13. The seal member 11 is constitutedby the seal lip portion 14 having the fuel side seal lip 15 brought intoslidable contact with the plunger 2 to mainly seal the fuel such asgasoline or the like at high pressure and the oil side seal lip 16brought into slidable contact with the plunger 2 and positioned in theopposite side B to the sealed object than the seal lip 15 to mainly sealthe oil for cooling and lubricating, and a seal fixing portion 17positioned in an outer peripheral side of the seal lip portion 14.Shapes of the fuel side seal lip 15 and the oil side seal lip 16 areboth formed in an approximately inverse-triangular cross sectional shapein which a center leading end portion protrudes in a diametricaldirection, and concave portions for installing the coil springs 31 and32 are formed in outer peripheral sides of leading end portions of theseal lips 15 and 16. The seal fixing portion 17 has a flange portion 17a extending in an outer peripheral direction from the seal lip portion14 and a cylinder portion 17 b extending to the opposite side B to thesealed object from a side surface of the flange portion 17 a, and isretained by the first metal ring 21, the second metal ring 22 and thethird metal ring. As a material of the seal member 11, a resin such asPTFE or the like which is excellent in a pressure resistance isemployed.

Two coil springs 31 and 32 are respectively installed to the concaveportions formed in the outer peripheral sides of the fuel side seal lip15 and the oil side seal lip 16, and apply energizing forces in adiametrical direction to the respective seal lips 15 and 16.

In the plunger seal 1 for the pump provided with the structure mentionedabove, since the material of the seal member 11 having the seal lip 15for sealing the fuel and the seal lip 16 for sealing the oil isconstituted by the resin material, and they are integrally formed so asto structure one seal system, a pressure resistance and an oilresistance are excellent, and the number of parts is reduced, and it ispossible to achieve a compact structure, a cost reduction and areduction of an assembling man-hour. Further, when a space P formed withrespect to the housing 3 in the side of the seal lip 15 for sealing thefuel comes to a high pressure, the retaining force of the seal fixingportion 17 is increased by pressing the flange portion 22 b of the metalring 22 attached in the inverse-L shape to the opposite side B to thesealed object from the sealed object side A in a direction of an arrowα. Accordingly, it is possible to improve a sealing performance.

Second Embodiment

FIG. 2 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a second embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 2, the seal fixing portion 17is pinched by an end surface formed by an expanded end surface of thehousing 3 and the first metal ring 21 as is different from the firstembodiment, and has a seal lip 17 a for sealing an inner peripheral sideof the metal ring 21. The other metal rings are not used. The fuel sideseal lip 15 has a sub lip 15 a. Further, since the shape of the oil sideseal lip 16 is formed in a rectangular cross sectional shape and thesealing performance is secured by contracting the oil side seal lip 16toward the opposite side B to the sealed object, no coil spring is used.

In the structure mentioned above, since the material of the seal member11 having the seal lip 15 for sealing the fuel and the seal lip 16 forsealing the oil is constituted by the resin material, and they areintegrally formed so as to structure one seal system, a pressureresistance and an oil resistance are excellent, and the number of partsis reduced, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour. Further, since thecoil spring is not used in the oil side seal lip 16, and only one metalring 21 is used, it is possible to achieve a further cost reduction anda further reduction of an assembling man-hour on the basis of thereduction of the number of the parts. Further, since the seal lip 17 afor sealing the inner peripheral side of the metal ring 21 is formed inthe seal fixing portion 17 so as to improve an air tightness, thepressure of the space P is further increased at a time when the space Pformed by the housing 3 in the side of the seal lip 15 for sealing thefuel comes to a high pressure. Accordingly, it is possible to increase afastening force of the seal lip 15 so as to improve a sealingperformance.

Third Embodiment

FIG. 3 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a third embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 3, the shape of the fuel sealmember 12 is different as is different from the second embodiment. Inother words, the fuel seal member 12 is formed in an approximatelyinverse-U cross sectional shape having a groove 41 open to the sealedobject side A, and is constituted by an outer peripheral fixing andsealing portion 42 fitted to the metal ring 21 fitted to the innerperipheral surface of the housing 2 and an inner peripheral fixing andsealing portion 43 having the seal lip 15 brought into slidable contactwith the plunger 3. A metal spring 33 for applying an energizing forcein a diametrical direction is inward provided in the groove 41. In thiscase, the sub lip 15 a is not provided.

The metal spring 33 is formed in an approximately U-shaped crosssection, and an end surface 33 a in an inner peripheral side leading endportion is locked to an end surface 44 a in an opposite side to thesealed object of the fixing collar 44 formed in an opening portion ofthe groove 41 and in a plunger side inner surface 41 a.

An axial position L1 at which the end surface 44 a of the fixing collar44 is formed in the opposite side A to the sealed object (a right sidein the drawing) than an axial position L2 of the leading end portion 15b of the seal lip 15. Accordingly, the structure is made such that anexpanding force of the metal spring 33 applied to the seal lip 15 ispositively utilized for controlling the surface pressure gradient Pgenerated on the contact surface of the seal lip 15 shown in FIG. 4, bycontrolling an axial distance C between the axial position L1 of the endsurface 44 a of the fixing collar 44 and the axial position L2 of theleading end portion 15 b of the seal lip 15.

In the structure mentioned above, it is possible to achieve the sameoperations and effects as those of the second embodiment. Further, sincethe fuel seal member 12 is made of the resin material, it is possible tosuppress a change level of the surface pressure gradient P bycontrolling the distance C between the axial position L1 where the endsurface 44 a of the fixing collar 44 is formed, and the axial positionL2 of the leading end portion 15 b of the seal lip 15, even in the casethat angles α and β formed by both side surfaces 15 c and 15 d of theseal lip 15 and the plunger 2 and defining the shape of the seal lip 15are deformed and changed due to a creep or an abrasion by use.

In this case, the fixing collar 44 formed in the inner surface of thegroove 41 may be provided at the housing 3 side in place of the plunger2 side.

Further, it is preferable that the distance C between the axial positionL2 of the leading end portion 15 b of the seal lip 15 and the axialposition L1 where the end surface 44 a of the fixing collar 44 is formedis 20% or less of the distance D between the axial position L2 of theleading end portion 15 b of the seal lip 15 and an axial position L3 ofa root portion 15 e of the seal lip 15, however, the distance is notlimited to this range.

Further, the description is given of the U-shaped metal spring 33,however, the kind of the spring is not limited to the metal spring, butevery kind of spring may be employed.

Fourth Embodiment

FIG. 5 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a fourth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 5, the fixing collar 44formed in the opening portion side of the groove 41 is formed in bothsides of the plunger side inner surface 41 a and a housing side innersurface 41 b, as is different from the third embodiment. The otherstructures are the same as the third embodiment. Accordingly, in thestructure mentioned above, it is possible to obtain the same operationsand effects as those of the third embodiment.

Fifth Embodiment

FIG. 6 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a fifth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 6, the seal member 11 isformed by the resin in such a manner that the fuel seal member 12 andthe oil seal member 13 are independent, as is different from the firstembodiment. The seal fixing portion 18 of the fuel seal member 12 andthe seal fixing portion 19 of the oil seal member 13, which areassembled to each other, the housing are pinched by an expanded endsurface of the housing 3 and the first metal ring 21, and the fuel sealmember 12 has a sub lip 15 a. The shape of the oil seal member 13 isformed in a rectangular cross sectional shape, and an energizing forceis applied by bringing the seal lip 16 into a slidable contact with theperipheral surface of the plunger 2 in such a manner as to bend the seallip 16 toward the opposite side B to the sealed object at the time ofinstallation. Accordingly, the coil spring is not used.

In the structure mentioned above, since the fuel side seal lip 15 andthe oil side seal lip 16 are made of the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, the coil spring is not used in the oil sealmember 13 and only one metal ring 21 is provided, the number of theparts is reduced at a time of assembling, and it is possible to achievea compact structure, a cost reduction and a reduction of an assemblingman-hour. Further, since the shape of the oil seal member 13 is notcomplicated so as to be easily processed, it is possible to achieve afurther cost reduction.

Sixth Embodiment

FIG. 7 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a sixth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 7, the fuel seal member 12 isformed in an approximately U-shaped cross section and is made of aresin, the seal fixing portion 18 is pinched by the first metal ring 21and the third metal ring 23 fitted to the housing 3, the energizingforce in the diametrical direction is applied by the U-shaped metalspring 33 provided within the groove 41 open to the sealed object side,and the sub lip 15 a is provided. As the used resin material, the resinsuch as the PTFE or the like having an excellent pressure resistance ispreferable. Further, the oil seal member 13 is made of a rubber, and theseal fixing portion 19 is adhered by vulcanization to an inner side ofthe second metal ring 22 made of the rubber and formed in anapproximately inverse-L shape. The seal lip 16 is integrally formed withthe seal fixing portion 19, is structured such as to be contractedtoward the opposite side to the sealed object while having a rectangularcross sectional shape so as to secure a sealing performance, and isprovided with a sub lip 16 a in the sealed object side A. The flangeportion 22 b of the second metal ring 22 supports the fuel seal member12 at the sealed object side, and the cylinder portion 22 a is fitted tothe inner peripheral side of the third metal ring 23. As a used rubbermaterial, a nitrile rubber, a hydrogenated nitrile rubber, an acrylicrubber, a fluorine-contained rubber, and a silicone rubber arepreferable, however, other synthetic rubbers may be employed.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin material, it is possible to obtainthe excellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain the excellent sealing performance. Since the fuelseal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofinstalling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour. Further, since thefuel seal member 12 is fixed by the seal fixing portion 18 beingpinched, and is also supported by the flange portion 22 b of the secondmetal ring 22 to which the seal fixing portion 19 of the oil seal member12 is adhered by vulcanization, behaviors of both the seal members 12and 13 in the annular space are small. Accordingly, it is possible toobtain a stable sealing performance under a condition of a highfrequency oscillation at a high pressure.

Further, in the same manner as the third embodiment, the fixing collar44 may be provided to protrude on the housing side inner surface 41 b inthe opening portion of the groove 41, and an outer peripheral sideleading end surface 33 b of the U-shaped metal spring 33 may be lockedto the end surface 44 a in the opposite side to the sealed object.

In this case, the axial position L1, at which the end surface 44 a ofthe fixing collar 44 is formed, is formed at the opposite side B to thesealed object (right side of the drawing) from the axial position L2 ofthe leading end portion 15 b of the seal lip 15. Accordingly, thestructure is made such that the expanding force of the metal spring 33applied to the seal lip 15 is positively utilized for controlling thesurface pressure gradient P generated on the contact surface of the seallip 15 shown in FIG. 4, by controlling the distance C between the axialposition L1 of the end surface 44 a of the fixing collar 44 and theaxial position L2 of the leading end portion 15 b of the seal lip 15.

In this structure, since the fuel seal member 12 is made of the resin,it is possible to suppress the change level of the surface pressuregradient P by controlling the distance C between the axial position L1at which the end surface 44 a of the fixing collar 44 is formed, and theaxial position L2 of the leading end portion 15 b of the seal lip 15,even in the case that the angles α and β formed by both the sidesurfaces 15 c and 15 d and the plunger 3 defining the shape of the seallip 15 are deformed and changed due to the creep or the abrasion by use.

In this case, it is preferable that the distance C between the axialposition L2 of the leading end portion 15 b of the seal lip 15, and theaxial position L1 at which the end surface 44 a of the fixing collar 44is formed is 20% or less of the distance D between the axial position L2of the leading end portion 15 b of the seal lip 15 and the axialposition L3 of the root portion 15 e of the seal lip 15, however, thedistance C is not limited to this range.

Seventh Embodiment

FIG. 8 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a seventh embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 8, the shape of the fuel sealmember 12 is different as is different from the sixth embodiment, andthe coil spring 31 is used for applying the energizing force.

In the structure mentioned above, since the material of the lip of thefuel seal member 12 is constituted by the resin material, it is possibleto obtain excellent pressure resistance and oil resistance. Further,since the material of the oil seal member 13 is constituted by therubber, it is possible to obtain an excellent sealing performance. Sincethe fuel seal member 12 and the oil seal member 13 are assembled so asto structure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofinstalling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour. Further, since thefuel seal member 12 is fixed by the seal fixing portion 18 beingpinched, and is also supported by the flange portion 22 b of the secondmetal ring 22 to which the seal fixing portion 19 of the oil seal member13 is adhered by vulcanization, the behaviors of both the seal members12 and 13 in the annular space are small. Accordingly, it is possible toobtain a stable sealing performance even under a condition of a highfrequency oscillation at a high pressure.

Eighth Embodiment

FIG. 9 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with an eighth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 9, since the fuel seal member12 is formed in a rectangular shape and made of a resin, the seal fixingportion 18 is pinched by the flange portion 21 b of the first metal ring21 and the flange portion 22 b of the second metal ring 22, and anenergizing force is applied by bringing the seal lip 15 into slidablecontact with the peripheral surface of the plunger 2 in such a manner asto bend the seal lip 15 to the sealed subject side A at a time ofinstalling, the coil spring is not used. The oil seal member 13 is madeof a rubber, the shape of the seal lip 16 is formed in a rectangularcross sectional shape, and is contracted toward the opposite side B tothe sealed object, and the sub lip 16 a is provided. The seal fixingportion 19 is adhered by vulcanization to the second metal ring 22 insuch a manner as to cover the cylinder portion 22 a of the second metalring 22. The cylinder portion 22 a of the second metal ring 22 is fittedto the inner peripheral side of the cylinder portion 21 a of the firstmetal ring 21 in the sealed object side A, and is fitted to the housing3 via the seal fixing portion 19 covering the cylinder portion 22 a ofthe second metal ring 22 in the opposite side B to the sealed object,and the flange portion 22 b is brought into contact with the seal fixingportion 18 of the fuel seal member 12 in the sealed object side A.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in both theseal members 12 and 13, the number of the parts is reduced at a time ofassembling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour. Particularly, sincethe shape of the fuel seal member 12 is not complicated and the fuelseal member 12 is easily processed, it is possible to obtain a greateffect of the cost reduction.

Ninth Embodiment

FIG. 10 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a ninth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 10, the shape of the fuelseal member 12 is different from the eighth embodiment. The fuel sealmember 12 has the seal lip 15 extending to the sealed object side A fromthe inner peripheral side end portion of the seal fixing portion 18 andformed in an approximately inverse-triangular cross sectional shape inwhich a center leading end portion protrudes in a diametrical direction,and the sub lip 15 a positioned in the opposite side to the sealedobject therefrom, and the coil spring 31 for applying an energizingforce in a diametrical direction is installed to a concave portionformed in an outer peripheral side of the seal lip 15.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofassembling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour.

Tenth Embodiment

FIG. 11 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a tenth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 11, the fuel seal member 12is formed by a resin material, and the seal fixing portion 18 and theseal lip 15 are integrally formed. The seal lip 15 has the seal the sublip 15 a extending to the sealed object side A from the inner peripheralside of the seal fixing portion 18, formed in an approximatelyinverse-triangular cross sectional shape in which a center leading endportion protrudes in a diametrical direction, and provided in theopposite side to the sealed object. Further, the coil spring 31 isinstalled to an outer peripheral side of the seal lip 15 for applying anenergizing force. The oil seal member 13 is constituted by the rubberseal lip 16 which is adhered by vulcanization to a leading end portionof an inner peripheral side flange portion 22 c of a step-shaped secondmetal ring 22. A shape of a leading end portion of the seal lip 16 isformed in a rectangular cross sectional shape, and is contracted towardthe opposite side B to the sealed object so as to secure a sealingperformance. The seal fixing portion 18 of the fuel seal member 12 andthe outer peripheral side flange portion 22 b of the second metal ringto which the seal lip 16 is adhered are pinched by the flange portions21 b and 21 c in both sides of the first metal ring 21 formed in anapproximately C-shaped cross section. The cylinder portion 21 a of thefirst metal ring 21 has a step in a center portion, a large-diametercylinder portion at the opposite side B to the sealed object is directlyfitted to the housing 3, and a small-diameter cylinder portion at thesealed object side A is fitted to the housing 3 via a fixing and sealingportion 24 adhered in such a manner as to cover the flange portion 21 bat the sealed object side A. The fixing and sealing portion 24 isintegrally provided with a seal lip 24 a extending to the sealed objectside A and brought into slidable contact with the inner peripheral sideend surface of the housing.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofassembling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour. Further, since theseal lip 24 a for sealing the inner peripheral end surface of thehousing 3 is formed in the fixing and sealing portion 24 and an airtightness is improved, it is possible to further increase the pressurein the space P at a time when the space P formed by the fuel seal member12 and the housing 3 comes to a high pressure. Accordingly, it ispossible to increase a fastening force of the seal lip 15, and it ispossible to improve a sealing performance.

Eleventh Embodiment

FIG. 12 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with an eleventh embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 12, the fuel seal member 12is formed by a resin material, and the seal fixing portion 18 and theseal lip 15 are integrally formed. The seal lip 15 extends to the sealedobject side A from the inner peripheral side of the seal fixing portion18, and is formed in an approximately inverse-triangular cross sectionalshape in which a center leading end portion protrudes in a diametricaldirection. Further, the coil spring 31 is installed to an outerperipheral side of the seal lip 15 for applying an energizing force. Theoil seal member 13 is constituted by the rubber seal lip 16 which isadhered by vulcanization to a leading end portion of a slope portion 23b extending diagonally toward the opposite side B to the sealed objectfrom an inner peripheral side end portion of a flange portion 23 a of athird metal ring 23. A shape of a leading end portion of the seal lip 16is formed in a rectangular cross sectional shape, and is contractedtoward the opposite side B to the sealed object so as to secure asealing performance. The seal fixing portion 18 of the fuel seal member12 and the flange portion 23 a of the third metal ring 23 to which theseal lip 16 is adhered are held by a first metal ring 21 fitted to theinner peripheral end surface of the housing 3, a flange portion 22 b ofthe second metal ring 22 fitted to an inner peripheral surface of thefirst metal ring 21, and an end surface of the expanded housing 3.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofassembling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour.

Twelfth Embodiment

FIG. 13 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a twelfth embodiment of the present invention.

In the plunger seal 1 for the pump in FIG. 13, the fuel seal member 12is formed in an approximately U shape, is made of a resin, and is fittedto an inner periphery of the first metal ring 21. A U-shaped metalspring 33 for applying an energizing force in a diametrical direction isinward provided in an inner portion of a groove 41 open to the sealedobject side A, and the fuel seal member 12 has a sub lip 15 a. The oilseal member 13 is constituted by the rubber seal lip 16 which is adheredby vulcanization to a leading end portion of a slope portion 21 cextending diagonally toward the opposite side B to the sealed objectfrom the inner peripheral side end portion of the flange portion 21 b ofthe first metal ring 21. A shape of the leading end portion of the seallip 16 is formed in a rectangular cross sectional shape, and iscontracted toward the opposite side B to the sealed object so as tosecure a sealing performance.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are assembled so as tostructure one seal system, and the coil spring is not used in the oilseal member 13, the number of the parts is reduced at a time ofassembling, and it is possible to achieve a compact structure, a costreduction and a reduction of an assembling man-hour.

Further, in the same manner as the fourth embodiment, the fixing collars44 may be provided to protrude on both side inner surfaces 41 a and 41 bin the opening portion of the groove 41, and the leading end surfaces 33a and 33 b of the U-shaped metal spring 33 may be locked to the endsurfaces 44 a at the opposite side to the sealed object of the fixingcollars 44.

In this case, the axial position L1, at which the end surfaces 44 a ofthe fixing collars 44 are formed, is formed at the opposite side B tothe sealed object (right side of the drawing) from the axial position L2of the leading end portion 15 b of the seal lip 15. Accordingly, thestructure is made such that the expanding force of the metal spring 33applied to the seal lip 15 is positively utilized for controlling thesurface pressure gradient P generated on the contact surface of the seallip 15 shown in FIG. 13, by controlling the distance C between the axialposition L1 of the end surfaces 44 a of the fixing collars 44 and theaxial position L2 of the leading end portion 15 b of the seal lip 15.

In this structure, since the fuel seal member 12 is made of the resin,it is possible to suppress the change level of the surface pressuregradient P by controlling the distance C between the axial position L1at which the end surfaces 44 a of the fixing collars 44 are formed, andthe axial position L2 of the leading end portion 15 b of the seal lip15, even in the case that the angles α and β formed by both the sidesurfaces 15 c and 15 d and the plunger 3 defining the shape of the seallip 15 are deformed and changed due to the creep or the abrasion by use.

Thirteenth Embodiment

FIG. 14 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a thirteenth embodiment of the presentinvention.

In the plunger seal 1 for the pump in FIG. 14, the fuel seal member 12is constituted by the resin seal lip 15. Since an outer peripheral sideof the seal lip 15 is fitted to the housing 3 in such a manner as tocompress a sealed object side position 19 a of a seal fixing portion 19of the rubber oil seal member 13 adhered by vulcanization so as to coverthe first metal ring 21, an energizing force is applied in a diametricaldirection on the basis of an elastic force generated by the portion 19 ato restore itself. The oil seal member 13 has a seal lip 16 integrallyformed with the seal fixing portion 19 and adhered by vulcanization tothe leading end of the inner peripheral side flange portion 21 c of thefirst metal ring, and a sub seal lip 16 a positioned in the sealedobject side A and formed in an approximately triangular cross sectionalshape in which a center leading end portion protrudes in a diametricaldirection. A shape of the leading end portion of the seal lip 16 isconstituted by a rectangular cross sectional shape, and the seal lip 16is contracted toward the opposite side B to the sealed object so as tosecure a sealing performance.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since andthe oil seal member 13 are assembled so as to structure one seal system,and the coil spring is not used in both the seal members 12 and 13, thenumber of the parts is reduced at a time of assembling, and it ispossible to achieve a compact structure, a cost reduction and areduction of an assembling man-hour. Particularly, since the shape ofthe fuel seal member 12 is not complicated and is easily processed, itis possible to obtain a great effect of the cost reduction.

Fourteenth Embodiment

FIG. 15 is a sectional view of a main portion of a plunger seal 1 for apump in accordance with a fourteenth embodiment of the presentinvention.

The plunger seal 1 for the pump in FIG. 15 is provided with the metalring 21 fitted to the inner periphery of the housing 3, the rubber oilseal member 13 adhered by vulcanization to the metal ring 21, the resinfuel seal member 12 fitted to the inner periphery of the metal ring 21,and a finger spring 5 installed to a portion between the metal ring 21and the fuel seal member 12.

The metal ring 21 is constituted by an outer peripheral side cylinderportion 21 a fitted to the inner periphery of the housing 3 and providedwith a projection portion 21 d on a terminal end at the sealed objectside A, a flange portion 21 b extending in an inner peripheral directionfrom a terminal end at the opposite side B to the sealed object of theouter peripheral side cylinder portion 21 a, and an inner peripheralside cylinder portion 21 c extending toward the opposite side B to thesealed object from an inner peripheral terminal end of the flangeportion 21 b.

In the oil seal member 13, a seal fixing portion 19, a seal lip 16, asub lip 16 a and a second seal lip 16 b are integrally formed. The sealfixing portion 19 is adhered to the inner peripheral side cylinderportion 21 c from the flange portion 21 b of the metal ring 21 and isbrought into close contact with the inner peripheral side end surface ofthe housing 3. The seal lip 16 extends toward the opposite side B to thesealed object from the seal fixing portion 19, mainly seals the oil, andhas a concave portion at an outer peripheral side for installing a coilspring 32 for applying an energizing force. The sub lip 16 a ispositioned at the sealed object side A from the seal lip 16. The secondseal lip 16 b extends to the sealed object side A from the seal fixingportion 19.

The fuel seal member 12 is constituted by a seal fixing portion 18fitted to an inner peripheral side of the outer peripheral side cylinderportion 21 a of the metal ring 21, and a seal lip 15 integrally formedwith the seal fixing portion 18, extending to the sealed object side,brought into contact with the plunger 2 and mainly sealing the fuel. Thefinger spring 5 is installed to a space formed by an outer peripheralside of the seal lip 15 and an inner peripheral side of the outerperipheral side cylinder portion 21 a of the metal ring 21. The fingerspring 5 applies an energizing force so as to energize the leading endportion 15 b of the seal lip 15 in a direction of the plunger 2, andbrings the leading end portion 5 a of the finger spring 5 into contactwith the projection portion 21 d of the outer peripheral side cylinderportion 21 a so as to regulate a distance at which the fuel seal member12 is movable in an axial direction.

In the structure mentioned above, since the material of the fuel sealmember 12 is constituted by the resin, it is possible to obtainexcellent pressure resistance and oil resistance. Further, since thematerial of the oil seal member 13 is constituted by the rubber, it ispossible to obtain an excellent sealing performance. Further, since thefuel seal member 12 and the oil seal member 13 are integrally formed soas to structure one seal system, it is possible to simplify thestructure of the housing 3 and it is possible to reduce an assemblingman-hour, at a time of assembling the plunger seal 1 for the pump in thehousing 3 corresponding to the opposite member. Further, since the fuelseal member 12 is movable to the sealed object side A so as to relievean accumulated pressure on the basis of a freedom of the finger spring5, at a time of accumulating pressure due to a small amount fuel leakfrom the fuel seal member 12, it is possible to reduce an abrasion ofthe oil seal member 13. Further, since the fuel seal member 12positioned in the sealed object side A from the oil seal member 13controls an excessive pressure and a pressure fluctuation operation, andthe second seal lip 16 b extending to the sealed object side A in theoil seal member 13 seals a small amount of fuel passing through the fuelseal member 12, it is possible to improve a sealing performance.

1. A seal for a plunger pump, the seal being provided in an annular space between a shaft reciprocating within a high-pressure fuel injection pump and a housing, said seal comprising a resin fuel seal member for sealing a high-pressure fuel in a side of a sealed object, a rubber oil seal member for sealing an oil in an opposite side to the sealed object, first and third metal rings fitted in said annular space, a second metal ring for separating said resin fuel seal member from said rubber oil seal member and for separating said rubber oil seal member from said third metal ring, and a metal spring member having a U-shape in cross-section and disposed in a groove in said resin fuel seal member, said resin fuel seal member including an outer peripheral side seal fixing portion having a rectangular cross sectional shape and clamped between said first and third metal rings in said annular space, an outer peripheral side fixing flange brought into contact with said first metal ring, and an inner peripheral side seal lip extending to the sealed object side from an inner peripheral end portion thereof and slidably brought into contact with the shaft to seal said high-pressure fuel, said groove in said resin fuel seal member being defined between said outer peripheral side fixing flange and said inner peripheral side seal lip, said rubber oil seal member being positioned in the opposite side to the sealed object side from said fuel seal member, and being slidably brought into close contact with said shaft to seal said oil, said metal spring member being adapted to apply a biasing force to said resin fuel seal member in a radial direction so as to press said outer peripheral side fixing flange to said first metal ring and to press said inner peripheral side seal lip to said shaft. 